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Flow Rate Converter

GPM • L/min • m³/h • L/s • CFM

Flow Rate ⓘ

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⚡ Quick Conversions — tap one

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Enter a flow rate to convert

How to Use the Flow Rate Converter

Enter a flow rate — a positive number.
Select From unit — GPM, L/min, m³/h, CFM, and more.
Select To unit — the unit you want the answer in.
Read the result — plus a quick grid in GPM, L/min, m³/h and CFM.
Use swap (⇄) — flip the conversion direction instantly.

Why Use This Flow Rate Converter

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US Gallons Clarified

GPM here is US gallons per minute (1 gal = 3.78541 L) — the standard for US plumbing, pumps and pools.

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Built for Real Jobs

Sized for plumbing, well pumps, pool turnover, aquariums, and HVAC airflow (CFM) in one tool.

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100% Private

All conversions run in your browser — no server, no account, nothing sent anywhere.

Flow Rate Conversion Guide — GPM, L/min, m³/h & CFM

Volumetric flow rate measures how much volume passes a point per unit time. In the US, water flow is usually given in gallons per minute (GPM), while the rest of the world uses liters per minute (L/min) or cubic meters per hour (m³/h). Airflow for HVAC and fans is measured in cubic feet per minute (CFM). Because a US gallon equals 3.78541 liters, the most common conversion — GPM to L/min — is simply multiplying by 3.78541.

Key conversions: 1 GPM = 3.785 L/min = 0.0631 L/s = 0.227 m³/h. 1 L/s = 15.85 GPM = 60 L/min = 3.6 m³/h. 1 m³/h = 4.403 GPM = 16.67 L/min. 1 CFM = 1.699 m³/h = 28.32 L/min. Note that US GPM differs from UK/Imperial GPM, because a UK gallon (4.54609 L) is about 20% larger than a US gallon — this converter uses US gallons throughout.

Real-world reference points: a typical kitchen faucet flows 1.5–2.2 GPM, a shower head 1.8–2.5 GPM (US efficiency standard caps shower heads at 2.5 GPM), a garden hose 9–17 GPM, and a residential well pump 8–12 GPM. Pool pumps move 40–80 GPM. For HVAC, a bathroom exhaust fan is around 50–110 CFM, while a whole-house furnace blower moves 1,000–2,000 CFM.

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Household Water

Kitchen faucet: 1.5–2.2 GPM. Shower: 1.8–2.5 GPM. Bathtub fill: 4–8 GPM. Garden hose: 9–17 GPM. Dishwasher: ~1 GPM. Washing machine: ~3–5 GPM during fill.

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Pools & Pumps

Pool pump: 40–80 GPM. Well pump: 8–12 GPM. To turn over a 20,000-gallon pool in 8 hours you need ~42 GPM. Aquarium filter: typically 4–10× tank volume per hour.

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HVAC Airflow (CFM)

Bathroom fan: 50–110 CFM. Range hood: 200–400 CFM. Furnace blower: 1,000–2,000 CFM. Rule of thumb: ~400 CFM per ton of AC cooling. 1 CFM = 1.699 m³/h.

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The Conversions

1 GPM = 3.785 L/min. 1 L/s = 15.85 GPM. 1 m³/h = 4.403 GPM. 1 CFS = 448.8 GPM. US gallon = 3.78541 L; UK gallon = 4.546 L (this tool uses US).

Flow Rate Conversion FAQ

How do I convert GPM to liters per minute? ▾

Multiply GPM by 3.78541, because one US gallon equals 3.78541 liters. So 10 GPM = 37.85 L/min, and 2.5 GPM (a standard shower head) = 9.46 L/min. To go the other way, divide L/min by 3.78541 to get US GPM. Note this uses the US gallon; if you have a UK/Imperial GPM figure, multiply by 4.54609 instead.

What is a normal household water flow rate? ▾

A typical kitchen faucet flows 1.5–2.2 GPM (5.7–8.3 L/min), a modern shower head is capped at 2.5 GPM (9.5 L/min) by US efficiency standards, and a garden hose delivers roughly 9–17 GPM depending on diameter and pressure. Total household demand during peak use is often estimated at 6–12 GPM, which is why well pumps are commonly sized around 8–12 GPM.

How do I convert CFM to m³/h? ▾

Multiply CFM by 1.699 to get cubic meters per hour. One cubic foot is 0.0283168 m³, and there are 60 minutes per hour, so 1 CFM = 0.0283168 × 60 = 1.699 m³/h. Example: a 100 CFM bathroom fan moves about 170 m³/h. To convert m³/h to CFM, divide by 1.699 (or multiply by 0.5886).

Is US GPM the same as UK GPM? ▾

No. A US gallon is 3.78541 liters while a UK (Imperial) gallon is 4.54609 liters — about 20% larger. So 10 US GPM = 37.85 L/min, but 10 UK GPM = 45.46 L/min. This converter uses US gallons throughout, which is the standard for US plumbing, pool, and pump specifications. If your equipment is rated in Imperial gallons, convert using the UK gallon factor.

How do I size a pool pump from turnover time? ▾

Divide the pool volume by the desired turnover time, then convert to per-minute. For a 20,000-gallon pool turned over once every 8 hours: 20,000 gal ÷ (8 × 60 min) = 41.7 GPM. Most residential pools aim for one to two turnovers per day. Once you know the required GPM, this converter gives you the equivalent L/min or m³/h to match a pump's spec sheet.